1. Technical Field
The present invention relates to a biasing circuit for a hall sensor and a hall amplifier in a motor driving circuit, and more particularly, to a biasing circuit for a hall sensor and a hall amplifier in a motor driving circuit capable of preventing deterioration of characteristics (performance) between the hall sensor and the hall amplifier in spite of a change in a process voltage temperature (PVT).
2. Description of the Related Art
A typical example of an image forming device which is a device performing generation, printing, reception, transmission, or the like, of image data may include a printer, a scanner, a copy machine, a facsimile, a multi-function device in which functions of the printer, the scanner, the copy machine, the facsimile are integrated, and the like.
The image forming device as described above uses motors in order to perform various functions such as movement of a printing paper, supply of the printing paper, and the like. Recently, as optional units performing various functions, such as an auto document feeder (ADF) unit, a finisher unit, a high capacity feeder (HCF) unit, and a double capacity feeder (DCF) unit may be attached to the image forming device, the number of motors that may be used in the image forming device has gradually increased.
Recently, a brushless DC (BLDC) motor has been mainly used in order to prevent noise generated at the time of driving the image forming device. In the BLDC motor, which is a motor that does not include a brush structure in a DC motor and electronically performs rectification, a mechanical friction part between a brush and a commutator is removed, such that a speed may increase and a small amount of noise is generated.
Since the BLDC motor does not the brush structure as described above, it requires a driving circuit in that position information of a rotor should be sensed using a hall sensor, or the like, and power should be sequentially applied to each phase of the BLDC motor to perform a control.
That is, in order to drive the motor, an additional motor driving circuit as well as a main controlling unit is required. In addition, the motor driving circuit should detect position information of an electromagnet used in the motor. To this end, a hall sensor capable of detecting magnetic field information of the electromagnet is used. The hall sensor is a component generating an output that is in proportion to a predetermined level or more of magnetic field intensity applied from the outside. In addition, since the hall sensor itself has a small output of several μV to several tens mV, a hall amplifier should be additionally used in an integrated circuit (IC). In this case, appropriate biasing should be applied to the hall sensor outside a chip and the hall amplifier inside of the chip to allow the motor driving circuit to maintain optimal performance in spite of a change in a process voltage temperature (PVT).